Methods and Systems for Channelization

ABSTRACT

Methods and systems are described that are suitable for channelization, in particular, but not limited to, the IEEE 80216.m telecommunications standard. For a time-frequency resource, physical sub-carriers for each of one or more zones in the time-frequency resource are assigned to one or more zones having a respective type of transmission. At least one zone is allocated for a type of transmission using localized sub-carriers. The physical sub-carriers assigned to each zone are permuted to map to logical sub-carriers. Groups of resource blocks are formed, in which each resource block includes at least one logical sub-carrier for each of the one or more zones. The information defining the groups of resource blocks for each of the one or more zones can then be transmitted to a user. The information may be in the form of a zone configuration index.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 60/986,166 filed on Nov. 7, 2007 and U.S. ProvisionalPatent Application No. 61/033,631 filed on Mar. 4, 2008, which are bothhereby incorporated by reference in their entirety.

FIELD OF THE INVENTION

The invention relates to channelization of wireless communicationsystems.

BACKGROUND OF THE INVENTION

Various wireless access technologies have been proposed or implementedto enable mobile stations to perform communications with other mobilestations or with wired terminals coupled to wired networks. Examples ofwireless access technologies include GSM (Global System for Mobilecommunications) and UMTS (Universal Mobile Telecommunications System)technologies, defined by the Third Generation Partnership Project(3GPP); and CDMA 2000 (Code Division Multiple Access 2000) technologies,defined by 3GPP2.

As part of the continuing evolution of wireless access technologies toimprove spectral efficiency, to improve services, to lower costs, and soforth, new standards have been proposed. One such new standard is theLong Term Evolution (LTE) standard from 3GPP, which seeks to enhance theUMTS wireless network. The CDMA 2000 wireless access technology from3GPP2 is also evolving. The evolution of CDMA 2000 is referred to as theUltra Mobile Broadband (UMB) access technology, which supportssignificantly higher rates and reduced latencies.

Another type of wireless access technology is the WiMax (WorldwideInteroperability for Microwave Access) technology. WiMax is based on theIEEE (Institute of Electrical and Electronics Engineers) 802.16Standard. The WiMax wireless access technology is designed to providewireless broadband access.

The existing control channel design used for the various wireless accesstechnologies discussed above are relatively inefficient. The controlchannel, which contains control information sent from a base station tomobile stations to enable the mobile stations to properly receivedownlink data and to transmit uplink data, typically includes arelatively large amount of information. In some cases, such controlchannels with relatively large amounts of information are broadcast tomultiple mobile stations in a cell or cell sector.

The overhead associated with such broadcasts of control channels makesusing such techniques inefficient, since substantial amounts ofavailable power and bandwidth may be consumed by the broadcast of suchcontrol channels. Note that the power of the broadcast control channelhas to be high enough to reach the mobile station with the weakestwireless connection in the cell or cell sector.

The control channel design in IEEE 802.16e, as a particular example isinefficient in both power and bandwidth. Since the control channel isalways broadcast to all users using full power with a frequency reusefactor of N=3, it consumes a significant portion of the available powerand bandwidth. Another disadvantage of the current control channeldesign is that it allows for many different signalling options, whichsignificantly increases the control channel overhead.

Although the control channel design in UMB and LTE is more efficient,both can be further optimized in order to reduce power and bandwidthoverhead.

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided a methodsuitable for channelization, the method comprising the steps of: for atime-frequency resource: assigning physical sub-carriers for each of oneor more zones in the time-frequency resource, each zone used for arespective type of transmission; permuting the physical sub-carriersassigned to each zone to map to logical sub-carriers; forming groups ofresource blocks including at least one logical sub-carrier for each ofthe one or more zones; and transmitting information defining the groupsof resource blocks for each of the one or more zones.

In some embodiments assigning physical sub-carriers for each of the oneor more zones in the time-frequency resource comprises assigningphysical sub-carriers to a zone used for distributed channeltransmission.

In some embodiments assigning physical sub-carriers for each of the oneor more zones in the time-frequency resource comprises assigningphysical sub-carriers to a zone used for frequency selective schedulingchannel transmission.

In some embodiments assigning physical sub-carriers for each of the oneor more zones in the time-frequency resource comprises assigningphysical sub-carriers to a zone used for at least one of: fractionalfrequency channel transmission; unicast single frequency network (SFN)channel transmission; network multiple input multiple output (MIMO)channel transmission; and multicast broadcast service (MBS) SFN channeltransmission.

In some embodiments permuting physical sub-carriers to map to logicalsub-carriers is performed using a zone specific permutation, whichdefines a mapping of the physical sub-carriers to logical sub-carriersfor a given zone.

In some embodiments transmitting information defining the groups ofresource blocks for each of the one or more zones comprises transmittinga zone configuration index in a control channel.

In some embodiments transmitting zone configuration index in a controlchannel of each of the one or more zones comprises: transmitting one of:a zone specific combination index, in which the order of the groups ofresource blocks for each of the one or more zones is unimportant; and azone specific permutation index, in which the order of the groups ofresource blocks for each of the one or more zones is important.

In some embodiments the time-frequency resource is an OFDM sub-frameincluding a plurality of OFDM symbols transmitted on a plurality ofsub-carriers.

In some embodiments a plurality of OFDM sub-frames comprise an OFDMframe, the method further comprising: allocating the plurality of OFDMsub-frames in the OFDM frame.

In some embodiments, wherein for multi-carrier operation, the methodcomprises: for each carrier, configuring a different channelizationdepending on the number of zones that are configured.

In some embodiments for multi-carrier operation, the method comprises:spanning channelization across multiple bands.

In some embodiments the method is for use with IEE802.16m.

In some embodiments the method further comprises, prior to permuting thephysical sub-carriers assigned to each zone to map to logicalsub-carriers: if there is at least one zone of the one or more zones fora type of transmission using localized sub-carriers, allocating at leastone zone of the one or more zones using localized sub-carriers beforeallocating at least one zone of the one or more zones for a type oftransmission using diversity sub-carriers.

In some embodiments, for uplink communication between a mobile stationand a base station: assigning physical sub-carriers for each of one ormore zones comprises assigning physical tiles, which are two dimensionaltime-frequency resources of at least one OFDM symbol over at least onesub-carrier, for each zone; permuting the physical sub-carriers assignedto each zone to map to logical sub-carriers comprises permuting thephysical tiles assigned to each zone to map to logical tiles; andforming groups of resource blocks, each resource block including atleast one logical sub-carrier for each of the one or more zonescomprises forming groups of resource blocks, each resource blockincluding at least one logical tile for each of the one or more zones.

In some embodiments the method further comprises: performinginterference coordination among neighbouring sectors as a function ofselection of the type of transmission signalling used in the one or morezones.

According to still another aspect of the invention, there is provided acomputer readable medium having stored thereon computer readableinstructions to be executed by a processor, the computer readableinstructions for: for a time-frequency resource: assigning physicalsub-carriers for each of one or more zones in the time-frequencyresource, each zone used for a respective type of transmission;permuting the physical sub-carriers assigned to each zone to map tological sub-carriers; forming groups of logical sub-carriers for each ofthe one or more zones; and transmitting information defining the groupsof logical sub-carriers for each of the one or more zones.

According to yet another aspect of the invention, there is provided amethod suitable for channelization, the method comprising the steps of:for a time-frequency resource defined as a frame that includes aplurality of sub-frames, each sub-frame having one or more zones,allocating the plurality of sub-frames in the frame; transmittinginformation defining the plurality of sub-frames; for each sub-frame,assigning physical sub-carriers for each of the one or more zones in thesub-frame, each zone used for a respective type of transmission;permuting the physical sub-carriers assigned to each zone to map tological sub-carriers; forming groups of logical sub-carriers for each ofthe one or more zones; and transmitting information defining the groupsof logical sub-carriers for each of the one or more zones.

According to yet a further aspect of the invention, there is provided atransmitter configured to implement any of the methods described above.

Other aspects and features of the present invention will become apparentto those ordinarily skilled in the art upon review of the followingdescription of specific embodiments of the invention in conjunction withthe accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described with reference to theattached drawings in which:

FIG. 1 is a block diagram of a cellular communication system on whichembodiments of the invention may be implemented;

FIG. 2 is a schematic diagram of a Downlink (DL) sub-frame according toan embodiment of the invention;

FIG. 3 is schematic diagram of an example pair of downlink (DL) framesaccording to an embodiment of the invention;

FIG. 4 is schematic diagram of another example of a pair of DL framesaccording to an embodiment of the invention;

FIG. 5A is a schematic diagram of an example of how physical uplink (UL)tiles are allocated for diversity and localized transmissions;

FIG. 5B is a schematic diagram of an example of how logical UL tiles areassigned to the physical UL tiles of FIG. 5A;

FIG. 6 is a flow chart describing a method for configuring zones in atime-frequency resource according to an embodiment of the invention;

FIGS. 7A, 7B and 7C are schematic diagrams illustrating an example ofhow zones are configured according to the method of FIG. 6;

FIG. 8 is a flow chart describing a method for configuring zones andsub-frames in a frame according to another embodiment of the invention;

FIGS. 9A and 9B are schematic diagrams of examples of time-frequencyresources allocated for multi-carrier operation according to differentembodiments of the invention;

FIG. 10 is a block diagram of an example base station that might be usedto implement some embodiments of the present invention;

FIG. 11 is a block diagram of an example wireless terminal that might beused to implement some embodiments of the present invention;

FIG. 12 is a block diagram of a logical breakdown of an example OFDMtransmitter architecture that might be used to implement someembodiments of the present invention; and

FIG. 13 is a block diagram of a logical breakdown of an example OFDMreceiver architecture that might be used to implement some embodimentsof the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

Described herein are embodiments of an inventive channelization schemeto enable an efficient control channel design. A control channel (whichmay also be referred to as a control segment) is used for assigningresources in a wireless communications network. A “control channel” or“control segment” refers to signalling or messaging for communicatinginformation used to control or enable communications between nodes ofthe wireless communications network. Some aspects of the presentinvention use an indexing method in the control channel to reducecontrol overhead.

For the purpose of providing context for embodiments of the inventionfor use in a communication system, FIG. 1 shows a base stationcontroller (BSC) 10 which controls wireless communications withinmultiple cells 12, which cells are served by corresponding base stations(DS) 14. In general, each base station 14 facilitates communicationsusing OFDM with mobile and/or wireless terminals 16 (also referred toherein as “users” or “UE”), which are within the cell 12 associated withthe corresponding base station 14. The individual cells may havemultiple sectors (not shown). The movement of the mobile terminals 16 inrelation to the base stations 14 results in significant fluctuation inchannel conditions. As illustrated, the base stations 14 and mobileterminals 16 may include multiple antennas to provide spatial diversityfor communications.

In the inventive resource management scheme, control of transmissionresource allocation may be performed for one or both of uplink (UL) anddownlink (DL). UL is transmitting in a direction from a mobile stationto a base station. DL is transmitting in a direction from the basestation to the mobile station.

DL Channelization

Control channel information for DL is implemented in a time-frequencyresource that is formed of multiple OFDM symbols, each transmitted onmultiple sub-carriers. An example of such a time-frequency resource is atransmission sub-frame. Multiple sub-frames can together form atransmission frame. The time-frequency resource is divided into one ormore zones. Each zone is used for transmitting to one or more users. Insome embodiments, the zones are formed based on the type of transmissionbeing transmitted. For example, some zones are used for diversitytransmissions, in which sub-carriers of the time-frequency resource arenon-contiguous and spread out over the available band of the zone. Otherzones may be used for localized transmissions, in which sub-carriers ofthe time-frequency resource are contiguous in the available band of thezone. The sub-carriers may be physical sub-carriers or logicalsub-carriers, which are physical sub-carriers that have been reorganizedbased on a permutation mapping. In some embodiments, sub-carriersbelonging to different zones are mutually exclusive, i.e. a sub-carrierdoes not belong to more than one zone. In some embodiments, multiplezones share the same sub-carrier.

As mentioned above, the zones in the time-frequency resource can be usedfor different types of DL transmissions.

Some particular examples of different types of DL transmissions include,but are not limited to: normal diversity transmissions; frequencyselective transmissions; fractional frequency reuse (FFR) transmissions;unicast Single Frequency Network (SFN) transmissions; network MIMOtransmissions; and multicast/broadcast service (MBS) SFN transmissions.

Diversity transmissions permits logical channel construction throughsub-carriers distributed across the band of available sub-carriers.

Frequency selective transmissions permit channel construction throughphysically adjacent (localized) sub-carriers. With frequency selectivetransmissions, adaptive matching of modulation, of coding, and of othersignal and protocol parameters, to conditions of a wireless link may beperformed to increase the likelihood of successful receipt of data by areceiving entity over a wireless link.

SFN transmissions utilize several transmitters simultaneously to sendthe same signal over the same frequency channel. SFN transmissions canbe used for unicast communication, which is communication between a basestation and a specific mobile station, or for multicast and/or broadcastcommunication, which is communication between a base station and allmobile stations in a given area (broadcast) or between a base stationand at least a select group of mobile stations in a given area(multicast).

FFR transmissions reuse some frequencies in non-adjacent sectors.

MIMO (multiple input/multiple output) transmissions utilize multipletransmitters at a base station and multiple receivers at a mobilestation and can be used for DL and/or UL communications.

In some embodiments, for unicast SFN, MBS SFN and Network MIMOtransmissions the allocation of physical sub-carriers is the same incorresponding zones in sectors that are involved in the SFN or networkMIMO zone transmissions.

In some embodiments, for FFR diversity transmissions the allocation ofphysical sub-carriers is different for different telecommunicationsectors in a cell in the network.

In some embodiments, each zone contains a control channel that indicateshow the resources within the zone are assigned to different users.

Some legacy IEEE802.16e systems use a time division multiplexing (TDM)approach for configuring diversity, localized and MIMO zones. Someembodiments of the present invention use a frequency divisionmultiplexing (FDM) approach, in which the channelization can span acrossall OFDM symbols of a zone in a sub-frame. Different zones areconfigured to use different portions of the band. Spanning thechannelization across all symbols allows for efficient power control ofboth control and traffic. Extended sub-frames can be defined toconcatenate the sub-channel resources across multiple sub-frames toreduce overhead and improve UL coverage, in particular for diversityallocation zones.

Referring to the figures, FIG. 2 illustrates one example embodiment ofhow a DL sub-frame may be configured. The DL sub-frame 130 includes fivezones 140,150,160,170,180. The zones are formed from one or moreresource blocks (RBs). In some embodiments, groups of one or more RBsform basic channel units (BCUs). BCUs are shown in zone 140 indicated byreferences 142, 146 and 148. BCU 148 is shown having three RBs indicatedby references 143,144,145. Each RB is formed of one or more sub-carriers(individual sub-carriers are not shown). A particular implementation ofa BCU is two RBs where each RB is 6 OFDM symbols, in which each OFDMsymbol utilizes 12 sub-carriers. In some embodiments, each zone spansover all symbols in the DL sub-frame 130.

Each zone 140,150,160,170,180 has a control channel 141,151,161,171,181that spans across the all the OFDM symbols of the respective zones. Thecontrol channel in each zone includes information that assigns thelocation of resources in the zone for specific users. For example,resources may be assigned using a combination of multicast message andseparate unicast messages for each assignment.

In the example of FIG. 2, the first three zones 140,150,160 are used forFFR channel assignments, the fourth zone 170 is used for frequencyselective channel assignments and the fifth zone 180 is a diversity zoneused for normal diversity channel assignments.

The zones defined in the FIG. 2 include logical sub-carriers. Logicalsub-carriers are physical sub-carriers that have been permuted based onzone specific and sector specific mappings.

The number of physical sub-carriers and OFDM symbols in an RB, thenumber of RBs in a zone, the number of RBs in a BCU, the number of BCUsin zone, the type of transmission allocated to each zone in a sub-frame,the number of zones in a sub-frame, and the arrangement of zones in thesub-frame are all examples of parameters that are implementationspecific.

To simplify the discussion of subsequent figures, the types of zonesconsistent with the zones defined in FIG. 2 have been identified asfollows in the subsequent figures. A first FFR transmission zoneconsistent with zone 140 is identified by reference character “R”, asecond FFR transmission zone consistent with zone 150 is identified byreference character “O”, a third FFR transmission zone consistent withzone 160 is identified by reference character “Y”, a frequency selectivetransmission zone consistent with zone 170 is identified by referencecharacter “G” and a normal diversity transmission zone consistent withzone 180 is identified by reference character “B”.

FIG. 3 illustrates a first example embodiment of two DL frames 210,220.A first frame 210 of the two frames includes a first frame header 212and a first frame body 214. A second frame 220 includes a second frameheader 222 and a second frame body 224. The second frame body 220include multiple sub-frames 230,232,234,236,238,240,242, wherein thehorizontal arrangement of the concatenated zones in FIG. 2 have beenrearranged in a vertical arrangement of concatenated zones. Thus thefrequency, i.e. the individual sub-carriers that form the RBs and zones,are represented along the vertical axis and time, which is representedby the number of OFDM symbols, is represented along the horizontal axis.In the illustrated example, sub-frames 230 and 240 are of similararrangement to sub-frame 100 illustrated in FIG. 2.

While only two frames are illustrated in FIG. 2, it is to be understoodthat the figure is merely exemplary of how two frames may be configuredin an overall series of frames that form a transmission between atransmitter and a receiver.

In some embodiments, each zone in FIG. 3 includes a number of RBs asdescribed above with reference to FIG. 2.

In some embodiments, the number and configuration of zones for eachsub-frame of a given frame is broadcast using a zone configuration indexas part of system information broadcast signaling. The systeminformation broadcast signaling is transmitted by the base stationeither periodically or when at least a portion of the system informationis changed. In some embodiments, the system information broadcastsignaling is sent on every frame. In some embodiments, the systeminformation broadcast signaling is sent in the beginning of the frame,for example as part of a frame header. Subsequent description of theinvention uses the frame header as an example for illustration purposes.This particular implementation does not preclude other means of sendingthe system information broadcast signaling.

In some embodiments, the respective frame headers 212 and 222 include acontrol channel consistent with that described in commonly owned patentapplication Ser. No. 12/202,741 filed Sep. 2, 2008, which isincorporated herein by reference in its entirety. The control cannel mayinclude for example a combination index and/or a permutation index asdescribed in U.S. patent application Ser. No. 12/202,741.

In some embodiments, the same number and configuration of zones is usedfor the duration of the frame.

In some embodiments, once the zones are defined, the ordering of thezones is permuted from sub-frame to sub-frame as shown in FIG. 3. Theordering of zones in a sub-frame will be referred to as a sub-frame zoneallocation pattern. In particular, the frame body 224 of frame 220includes seven sub-frames. The same sequential order of zones is seen ineach sub-frame, that being “ROYGB”, but the pattern is cyclicallyshifted or advanced by one zone in each subsequent sub-frame. In thefirst sub-frame 230, the R type zone is located in the first zone (topzone in the column of zones) of sub-frame 230 and the B type zone is thelast zone (bottom zone in the column of zones) in sub-frame 230. In thesecond sub-frame 232, the R type zone is the second zone, the other zonetypes are similarly shifted down by one zone and the B type zone, whichwas the last zone in sub-frame 230, is in the first zone in sub-frame232. This continues for each subsequent sub-frame in the illustratedexample.

In the example of FIG. 3, during frame 210, base stations in the networkcoordinate and define the number and configuration of zones for thesubsequent frame, which is frame 220. In the illustrated example, thezone definitions include three FFR transmission zones R, O, Y, afrequency selective transmission zone G and a normal diversitytransmission zone B.

The configuration of zones in frame 220, which is defined during frame210, is broadcast to the mobile stations in frame header 212 of frame220. In some embodiments, this configuration information is sent as azone configuration index. The configuration of the zones may refer toone or both of the physical sub-carrier to logical sub-carrierpermutation and/or the ordering of zones in the sub-frame.

For each zone, as described above, a control channel then providesadditional information regarding the assignment of resources for thezone to respective users.

In some embodiments, the size of the frame header, the size of the framebody, the number of sub-frames in a frame, the configuration of zones,and types of transmission zones in the sub-frames of the respectiveframe are each parameters that are implementation specific.

FIG. 4 illustrates a second example embodiment of two DL frames 210,320.Frames 210 and 320 have frame bodies 214,324 and frame headers 212,322.During frame 210, base stations in the network coordinate and define thezones for frame 320. The various zones included in frame 320 are threeFFR transmission zones R, O, Y, two zones for frequency selectivetransmissions, both identified as G, and a normal diversity transmissionzone B.

In FIG. 4, only two sub-frame zone allocation patterns are defined,specifically “GRGOYB” as illustrated in sub-frames 330,334,338 and 342and “YGRGOB”, as illustrated in sub-frames 332,336, and 340, whichalternate from sub-frame to sub-frame.

Each zone in the illustrated example of FIG. 4 includes multiple RBs, asdescribed above with reference to FIG. 2.

In some embodiments all the RBs in a zone have the same number ofsub-carriers. In the zones used for frequency selective channelassignment, an RB is formed from contiguous physical sub-carriers.

In the zones used for diversity channel assignment, a RB is formed fromphysical sub-carriers that are distributed over the entire band ofsub-carriers that are available, which may be referred to as logicalsub-carriers.

In some embodiments, the physical sub-carrier to logical sub-carrierpermutation is sector specific, that is, different sectors of a cellhave different and distinct physical to logical sub-carrierpermutations. In some embodiments, the physical sub-carrier to logicalsub-carrier permutation is a common to multiple sectors.

In some embodiments, a given zone is indicated to be a diversity zone ora frequency selective zone by using one or more bits in the systeminformation broadcast signaling. For example, a single bit, “0”indicating a diversity zone and “1” indicating a frequency selectivezone, is used to indicate whether a zone is a diversity or frequencyselective zone.

UL Channelization

A UL RB is a time-frequency resource that is formed of multiple ULtiles. Each tile is a given number of OFDM symbols on one or moresub-carriers. The sub-carriers in the band may be a group of contiguoussub-carriers. A particular example of a tile is six OFDM symbols on sixsub-carriers.

Each UL tile contains dedicated pilot sub-carriers. A UL RB can beformed from one or more UL tiles of a single zone.

In some embodiments, the use of multiple zones aids in interferencemitigation coordination among neighbouring sectors. For example, usingdifferent physical sub-carrier to logical sub-carrier permutations inthe multiple zones may aid in reducing interference between adjacentsectors. In some embodiments, the number of zones and the configurationof the zones are signaled in a frame header for each sub-frame in theframe. The configuration of the zones may refer to the sub-frame zoneallocation pattern. In some embodiments, such information is sent in thecontrol channel described in U.S. patent application Ser. No.12/202,741, as mentioned above.

Referring to FIGS. 5A and 5B, an example of how tiles are allocated todiversity and localized zones and how particular zone types are assignedto those diversity and localized zones will now be discussed.

FIG. 5A illustrates an example embodiment of the physical location of ULtiles assigned to zones, each zone having at least one logical tile.Logical tiles are formed by permuting physical tiles.

The example in FIG. 5A shows the physical location of the UL tiles for agiven time-frequency resource. The physical tiles in the time-frequencyresource are allocated as either a diversity assignment zone, indicatedby tiles having the reference character D, or as a frequency selective(localized) assignment zone, indicated by tiles having a referencecharacter L.

FIG. 5A illustrates a diversity assignment zone 400 having nine tiles,followed by a localized assignment zone 410 having seven tiles, followedby another diversity assignment zone 420 having nine tiles.

The assignment of the number of physical tiles to each zone can changefrom time to time, e.g. symbol to symbol, set of symbols to set ofsymbols, frame to frame, etc. In some embodiments, the same ordering ofzones is allocated across multiple sectors of a cell and the physicaltiles mapped to each zone are the same across all the sectors involved.

FIG. 5B shows how particular zone types are assigned to the distributedand localized assignment zones 400, 410,420 of FIG. 5A.

The mapping of localized zone type G tiles, which are frequencyselective transmission type tiles, to physical tile locations L shown inFIG. 5A, is performed in a sequential order. Therefore, a sequentialgrouping of localized zone type G tiles is assigned to the 7 tiles ofthe localized assignment zone 410.

The mapping of diversity zone type R, O, Y tiles, which are threeparticular FFR transmission type tiles, to physical tile locations Dshown in FIG. 5A, is performed by permuting the diversity zones R, O, Yaccording to a sector specific tile assignment pattern “ROY”. As shownin FIG. 5B, the diversity zone type R, O, Y tiles are assigned to thefirst and second sets of the 9 tiles of the diversity assignment zones400,420 using the tile assignment pattern “ROY”, repeated three times ineach of the 9 tile groups. Specifically, in FIG. 5B it can be seen thatthe diversity zone type R tiles 430 are located in every third tileassigned to the diversity assignment zone, i.e. in the first, fourth andseventh tiles, the diversity zone type O tiles 440 are located in thesecond, fifth and eighth tiles, and the diversity zone type Y tiles 450are located in the third, sixth and ninth tiles.

If there are multiple diversity zones for the purpose of interferencecoordination between sectors of the network then each correspondingdiversity zone across sectors of the network involved in interferencecoordination should consist of the same physical tile locations, but thetile assignment pattern used to map the logical tiles of the respectivediversity type zones to the physical tile locations is sector specific.

Once the zone type tiles are assigned to the physical locations, D or L,partitions within the zone type are formed using logical tiles. Thiswill be described in further detail below.

The size of a UL resource used for channelization, the number of tiles,the size of tiles, the grouping of tiles for localized and distributedtransmissions, the number and type of zones are all examples ofimplementation specific parameters.

Zone Configuration Signalling

In some embodiments, the configuration of the zones for a frame issignaled in the frame header. In some embodiments, the configuration issignaled using a zone configuration index.

The zone configuration index may be a value representative in a look-uptable of predefined configurations that indicate the size, type andnumber of zones per sub-frame.

In some implementations, a zone configuration index is a permutationindex, PI. The PI represents a vector in which for a predefined order ofzones, the number of BCUs in each different type of zones is defined. Asan example, a predefined order of zones used in a vector to define thezones in a sub-frame is [D, DFFR1, DFFR2, DFFR3, L, LFFR1, LFFR2,LFFR3], where: D is a normal diversity allocation zone; DFFR1 is a firstdiversity FFR allocation zone; DFFR2 is a second diversity FFRallocation zone; DFFR3 is a third diversity FFR allocation zone; L isnormal localized allocation zone; LFFR1 is a first localized FFRallocation zone; LFFR2 is a second localized FFR allocation zone; andLFFR3 is a third localized FFR allocation zone.

By way of further example, a particular vector defining a sub-framebased on the above defined vector is [1 4 3 0 3 1 0 2], which definesthe D zone having 1 RB, the DFFR1 zone having 4 RBs, the DFFR2 zonehaving 3 RBs, the DFFR3 zone having 0 RBs, the L zone having 3 RBs, theLFFR1 zone having 1 RB, the LFFR2 zone having 0 RBs, and the LFFR3 zonehaving 2 RBs. In some embodiments, the resultant vector [1 4 3 0 3 1 02] is used directly as the PI. In some embodiments, the resultant vector[1 4 3 0 3 1 0 2] is used to determine a representative value to be usedas the PI, for example an integer value, which may be expressed as abinary number.

For a vector having a given list of zone types, if certain types ofzones are not included in a given sub-frame, the number of RBs for thatzone type would be 0.

The above description is for exemplary purposes and is not intended tolimit the scope of the invention. In a real world implementation theremay be fewer types of zones defined in a vector, additional types ofzones defined in a vector, or types of zones not specifically identifiedin the above example. In addition, the order of the types of zones andnumber of RBs per zone are examples of implementation specificparameters.

In some embodiments, to reduce the number of permutations, the number ofRBs per zone is a multiple of k, where k is an integer greater than zerosuch that the total number of RBs in a respective sub-frame is divisibleby k.

The resource allocation index indicates the order of the zones based onthe pre-determined order of the zone types in the vector.

Since the physical sub-carrier to logical sub-carrier permutation iseither sector specific or common to more than one sector, it is alsosignaled in the frame header.

Procedure for Zone Configuration

A method for DL channelization with now be described with reference tothe flow chart of FIG. 6 and schematic diagrams of FIGS. 7A, 7B and 7Cillustrating the result of the respective method steps, for a particularexample of zone configuration.

Referring back to the description of FIGS. 3 and 4, in which it wasdescribed that base stations in the network coordinate and define thenumber and configuration of zones for a subsequent frame, it may beconsidered that steps in the flow chart of FIG. 6 described below areperformed during a subsequent frame to the frame for which thechannelization is being arranged.

In FIG. 6, step 6-1 involves assigning physical sub-carriers for each ofone or more zones in a space-time frequency resource, each zone used fora respective type of transmission. Contiguous sub-carriers are allocatedto localized transmission type zones and evenly distributed sub-carriersare allocated for distributed transmission type zones. In someembodiments, “evenly” distributed means the sub-carriers have aperiodic, or at least, reoccurring spacing.

FIG. 7A shows allocation of physical sub-carrier locations to fourdistributed allocation zone types R, O, Y, B, having a repetitivesub-carrier allocation pattern of “ROYB”. In the repetitive sub-carrierallocation pattern every fifth physical sub-carrier location is assignedto the same zone type. FIG. 7A also shows allocation of physicalsub-carrier locations to single localized allocation zone type G. Thesub-carrier allocation shown in FIG. 7A is for one OFDM symbol 710 inthe sub-frame. The remaining OFDM symbols in the sub-frame are allocatedto the different zones similarly. The localized zones are formed usingthe same sub-carriers across all OFDM symbols. The diversity zones canuse a different sub-carrier mapping across OFDM symbols in a sub-frame.

The first 20 sub-carriers of OFDM symbol 710 starting from left to rightare allocated for diversity transmission, the subsequent 8 sub-carriersare allocated for localized transmission and the subsequent 28sub-carriers are allocated for diversity transmission. The R typesub-carriers are spaced apart in a manner that every fifth sub-carrierlocation is allocated to an R type sub-carrier in the first 20sub-carriers. The sub-carriers which are allocated for R type zonetransmissions are indicated by references 722 a-722 c, 724 a-724 c, 726a-726 c, 728 a-728 c. Similar allocation is done for the 0, Y and Bsub-carriers. Therefore, a first physical sub-carrier location isassigned for R zone type transmission 722A, a second physicalsub-carrier location is assigned for 0 zone type transmission 724A, athird physical sub-carrier location is assigned for Y zone typetransmission 726A, a fourth physical sub-carrier location is assignedfor B zone type transmission 728A, a fifth physical sub-carrier locationis assigned for R zone type transmission 722B, etc.

The sub-carrier locations used for localized allocation zone type G areallocated to the 8 contiguous sub-carrier locations allocated forlocalized transmission.

In some embodiments, the same set of zones are configured acrossmultiple sectors and the physical sub-carrier locations mapped to eachzone are the same across the sectors involved.

In some embodiments, the allocation of zone types to physicalsub-carrier locations can change occasionally, for example, symbol tosymbol, set of symbols to set of symbols, frame to frame, etc.

Step 6-2 involves allocating at least one zone of the one or more zonesfor a transmission type that uses localized sub-carriers. If there areno transmission types that use localized sub-carriers, then step 6-2 isnot performed. In some embodiments, each of one or more localizeddiversity zones is allocated a particular zone in the time-frequencyresource. In some embodiments, if there is at least one zone of the oneor more zones for a type of transmission using localized sub-carriers,allocating at least one zone of the one or more zones using localizedsub-carriers before allocating at least one zone of the one or morezones for a type of transmission using diversity sub-carriers.

Step 6-3 involves, once the zones are allocated to a set of physicalsub-carrier locations, permuting the physical sub-carriers assigned toeach zone so as to map to logical sub-carriers. The allocatedsub-carriers for a given zone are permuted with a sector specificpermutation and/or zone specific permutation to map to the logicalsub-carriers.

FIG. 7B illustrates how the physical sub-carriers are permuted tological sub-carriers. In the particular example of the R type zonesub-carriers, all of the R type zone sub-carriers 722 a-722 c, 724 a-724c, 726 a-726 c, and 728 a-728 c from OFDM symbol 710 are groupedtogether, along with the R type zone sub-carriers from other OFDMsymbols, as collectively indicated by reference 720. Similarly, all ofthe O type zone sub-carriers are grouped together, as collectivelyindicated by reference 730, all of the Y type zone sub-carriers aregrouped together, as collectively indicated by reference 740, and all ofthe B type zone sub-carriers are grouped together, as collectivelyindicated by reference 750. All of the G type zone sub-carriers aregrouped together, as collectively indicated by reference 760. There are12 logical sub-carriers, individually shown in FIG. 7A, that form thecomplete R type zone in 720 of FIG. 7B. The same is true for the 0, Yand B type zones. There are 8 logical sub-carriers, individually shownin FIG. 7A, that form the G type zone in 760 of FIG. 7B.

Step 6-4 involves forming groups of RBs for each zone where each RBincludes a set of logical sub-carriers. The groups of RBs may be knownas basic channel units. In some embodiments the DCUs ordered list ofRBs.

FIG. 7C illustrates the grouping of RBs for each zone type, in whicheach RB is formed of multiple sub-carriers. For example, references762A,762 b,762C are each RBs that form a first BCU 762, references764A,764B,764C are each RBs that form a second BCU 764, references766A,766B,766C are each RBs that form a third BCU 766 and references768A,768 b,768C are each RBs that form a fourth BCU 768. A similar typeof grouping is performed for each of zones O, Y, B and G.

Step 6-5 involves transmitting information defining the groups of RBsfor each of the one or more zones.

In some embodiments, transmitting information defining the groups of RBsin a control channel of each of the one or more zones comprisestransmitting one of: a zone specific combination index, in which theorder of the arrangement of groups of logical sub-carriers for each ofthe one or more zones is unimportant and a zone specific permutationindex, in which the order of the arrangement of groups of logicalsub-carriers for each of the one or more zones is important.

The method illustrated in FIG. 6 is described for use in DLchannelization. A similar method could be implemented for ULchannelization in which the physical sub-carriers and logicalsub-carriers of DL channelization would more appropriately be referredto as physical tiles and logical tiles for UL channelization and thegroups of logical sub-carriers of DL channelization would moreappropriately be referred to as groups of logical tiles for ULchannelization.

The number of physical sub-carriers/tiles in an RB, the number of RBs ina zone, the number of BCUs in a zone, the number and type of zones in asub-frame, and the arrangement of different types of zones in thesub-frame are all examples of implementation specific parameters.

Reference will now be made to FIG. 8, which illustrates a furtherexample of a method according to an embodiment of the present invention.The method illustrated in FIG. 8 is directed to defining the sub-framesin a frame in addition to defining the zones in a sub-frame.

In some embodiments a zone configuration index is used to define thechannelization of one or more sub-frames. For example, the zoneconfiguration may be associated with an integer value in a look-uptable, accessible to the base station and/or mobile station, thatdefines the channelization of one or more sub-frames.

The zone configuration is then used, in the system information broadcastsignaling discussed above with reference to FIGS. 3 and 4 to define thechannelization of sub-frames in one or more frames in the mannerdescribed.

Step 8-1 involves for a frame that includes a plurality of sub-frames,in which each sub-frame has one or more zones, allocating the pluralityof sub-frames in the frame.

Step 8-2 involves transmitting information defining the plurality ofsub-frames.

Step 8-3 involves for each sub-frame, assigning physical sub-carriersfor each of one or more zones in the sub-frame, each zone used for arespective type of transmission.

Step 8-4 involves allocating at least one zone of the one or more zonesfor a transmission type that uses localized sub-carriers. If there areno transmission types that use localized sub-carriers, then step 6-2 isnot performed. In some embodiments, each of one or more localizeddiversity zones is allocated a particular zone in the time-frequencyresource. In some embodiments, if there is at least one zone of the oneor more zones for a type of transmission using localized sub-carriers,allocating at least one zone of the one or more zones using localizedsub-carriers before allocating at least one zone of the one or morezones for a type of transmission using diversity sub-carriers.

Step 8-5 involves permuting the physical sub-carriers assigned to eachzone to map to logical sub-carriers.

Step 8-6 involves forming groups of RBs for each of the one or morezones.

Step 8-7 involves transmitting information defining the groups of RBsfor each of the one or more zones.

Steps 8-3, 8-4, 8-5 and 8-6 are substantially the same as steps 6-1,6-2, 6-3 and 6-4 of FIG. 6, wherein the time-frequency resource of FIG.6 is defined as sub-frame.

While FIG. 8 illustrates a particular sequence to the steps, this is notintended to limit the scope of the invention. In some embodimentsalternative sequences of steps are contemplated. For example, steps 8-1,8-3, 8-4 and 8-5 may be performed sequentially and once these steps havebeen performed, the transmitting steps 8-2 and 8-6 may be performed. Insome embodiments step 8-2 is the transmission of a portion of the frameheader and step 8-6 is the transmission of a control channel in therespective zone of each sub-frame.

In multi-carrier, for example network MIMO, operation there aredifferent ways to implement channelization. Two examples are shown inFIGS. 9A and 9B.

In some embodiments, each carrier has a different channelizationdepending on the number of zones that are configured. In this case, eachcarrier will have a separate control channel. FIG. 9A shows atime-frequency resource 910 having two zones, one for each carrier. Eachzone has its own control channel 920,930 and data transmission zone925,935.

In the illustrated example, each zone is shown to be 5 MHz. This is notintended to limit the invention, but for example purposes only.

In some embodiments, the channelization can span multiple bands. In thiscase, a single control channel can be used. Such a configuration may beused to transmit to a wide band user, when no support is needed fornarrow band users. FIG. 9B shows a time-frequency resource 940 having asingle zone for one wideband user, i.e. 10 MHz in place of the two 5 MHznarrow bans users of FIG. 9A. The single zone has one control channel950 and a data transmission zone 960.

The methods and systems described above may be implemented fortransmitting information according to IEEE802.16m. While IEEE 802.16m isa particular telecommunications standard, it is to be understand thatthe principles of the invention as described herein could be used withother types of standards that may benefit from aspects of the invention.

Description of Example Components of a Relay System

A high level overview of the mobile terminals 16 and base stations 14upon which aspects of the present invention are implemented is providedprior to delving into the structural and functional details of thepreferred embodiments. With reference to FIG. 10, a base station 14 isillustrated. The base station 14 generally includes a control system 20,a baseband processor 22, transmit circuitry 24, receive circuitry 26,multiple antennas 28, and a network interface 30. The receive circuitry26 receives radio frequency signals bearing information from one or moreremote transmitters provided by mobile terminals 16 (illustrated in FIG.1). A low noise amplifier and a filter (not shown) may co-operate toamplify and remove broadband interference from the signal forprocessing. Downconversion and digitization circuitry (not shown) willthen downconvert the filtered, received signal to an intermediate orbaseband frequency signal, which is then digitized into one or moredigital streams.

The baseband processor 22 processes the digitized received signal toextract the information or data bits conveyed in the received signal.This processing typically comprises demodulation, decoding, and errorcorrection operations. As such, the baseband processor 22 is generallyimplemented in one or more digital signal processors (DSPs) orapplication-specific integrated circuits (ASICs). The receivedinformation is then sent across a wireless network via the networkinterface 30 or transmitted to another mobile terminal 16 serviced bythe base station 14.

On the transmit side, the baseband processor 22 receives digitized data,which may represent voice, data, or control information, from thenetwork interface 30 under the control of control system 20, and encodesthe data for transmission. The encoded data is output to the transmitcircuitry 24, where it is modulated by a carrier signal having a desiredtransmit frequency or frequencies. A power amplifier (not shown) willamplify the modulated carrier signal to a level appropriate fortransmission, and deliver the modulated carrier signal to the antennas28 through a matching network (not shown). Various modulation andprocessing techniques available to those skilled in the art are used forsignal transmission between the base station and the mobile terminal.

With reference to FIG. 11, a mobile terminal 16 configured according toone embodiment of the present invention is illustrated. Similarly to thebase station 14, the mobile terminal 16 will include a control system32, a baseband processor 34, transmit circuitry 36, receive circuitry38, multiple antennas 40, and user interface circuitry 42. The receivecircuitry 38 receives radio frequency signals bearing information fromone or more base stations 14. A low noise amplifier and a filter (notshown) may co-operate to amplify and remove broadband interference fromthe signal for processing. Downconversion and digitization circuitry(not shown) will then downconvert the filtered, received signal to anintermediate or baseband frequency signal, which is then digitized intoone or more digital streams.

The baseband processor 34 processes the digitized received signal toextract the information or data bits conveyed in the received signal.This processing typically comprises demodulation, decoding, and errorcorrection operations. The baseband processor 34 is generallyimplemented in one or more digital signal processors (DSPs) andapplication specific integrated circuits (ASICs).

For transmission, the baseband processor 34 receives digitized data,which may represent voice, data, or control information, from thecontrol system 32, which it encodes for transmission. The encoded datais output to the transmit circuitry 36, where it is used by a modulatorto modulate a carrier signal that is at a desired transmit frequency orfrequencies. A power amplifier (not shown) will amplify the modulatedcarrier signal to a level appropriate for transmission, and deliver themodulated carrier signal to the antennas 40 through a matching network(not shown). Various modulation and processing techniques available tothose skilled in the art are used for signal transmission between themobile terminal and the base station.

In OFDM modulation, the transmission band is divided into multiple,orthogonal carrier waves. Each carrier wave is modulated according tothe digital data to be transmitted. Because OFDM divides thetransmission band into multiple carriers, the bandwidth per carrierdecreases and the modulation time per carrier increases. Since themultiple carriers are transmitted in parallel, the transmission rate forthe digital data, or symbols, on any given carrier is lower than when asingle carrier is used.

OFDM modulation utilizes the performance of an Inverse Fast FourierTransform (IFFT) on the information to be transmitted. For demodulation,the performance of a Fast Fourier Transform (FFT) on the received signalrecovers the transmitted information. In practice, the IFFT and FFT areprovided by digital signal processing carrying out an Inverse DiscreteFourier Transform (IDFT) and Discrete Fourier Transform (DFT),respectively. Accordingly, the characterizing feature of OFDM modulationis that orthogonal carrier waves are generated for multiple bands withina transmission channel. The modulated signals are digital signals havinga relatively low transmission rate and capable of staying within theirrespective bands. The individual carrier waves are not modulateddirectly by the digital signals. Instead, all carrier waves aremodulated at once by IFFT processing.

In operation, OFDM is preferably used for at least down-linktransmission from the base stations 14 to the mobile terminals 16. Eachbase station 14 is equipped with “n” transmit antennas 28, and eachmobile terminal 16 is equipped with “m” receive antennas 40. Notably,the respective antennas can be used for reception and transmission usingappropriate duplexers or switches and are so labelled only for clarity.

With reference to FIG. 2, a logical OFDM transmission architecture willbe described. Initially, the base station controller 10 will send datato be transmitted to various mobile terminals 16 to the base station 14.The base station 14 may use the channel quality indicators (CQIs)associated with the mobile terminals to schedule the data fortransmission as well as select appropriate coding and modulation fortransmitting the scheduled data. The CQIs may be directly from themobile terminals 16 or determined at the base station 14 based oninformation provided by the mobile terminals 16. In either case, the CQIfor each mobile terminal 16 is a function of the degree to which thechannel amplitude (or response) varies across the OFDM frequency band.

Scheduled data 44, which is a stream of bits, is scrambled in a mannerreducing the peak-to-average power ratio associated with the data usingdata scrambling logic 46. A cyclic redundancy check (CRC) for thescrambled data is determined and appended to the scrambled data usingCRC adding logic 48. Next, channel coding is performed using channelencoder logic 50 to effectively add redundancy to the data to facilitaterecovery and error correction at the mobile terminal 16. Again, thechannel coding for a particular mobile terminal 16 is based on the CQI.In some implementations, the channel encoder logic 50 uses known Turboencoding techniques. The encoded data is then processed by rate matchinglogic 52 to compensate for the data expansion associated with encoding.

Bit interleaver logic 54 systematically reorders the bits in the encodeddata to minimize the loss of consecutive data bits. The resultant databits are systematically mapped into corresponding symbols depending onthe chosen baseband modulation by mapping logic 56. Preferably,Quadrature Amplitude Modulation (QAM) or Quadrature Phase Shift Key(QPSK) modulation is used. The degree of modulation is preferably chosenbased on the CQI for the particular mobile terminal. The symbols may besystematically reordered to further bolster the immunity of thetransmitted signal to periodic data loss caused by frequency selectivefading using symbol interleaver logic 58.

At this point, groups of bits have been mapped into symbols representinglocations in an amplitude and phase constellation. When spatialdiversity is desired, blocks of symbols are then processed by space-timeblock code (STC) encoder logic 60, which modifies the symbols in afashion making the transmitted signals more resistant to interferenceand more readily decoded at a mobile terminal 16. The STC encoder logic60 will process the incoming symbols and provide “n” outputscorresponding to the number of transmit antennas 28 for the base station14. The control system 20 and/or baseband processor 22 as describedabove with respect to FIG. 10 will provide a mapping control signal tocontrol STC encoding. At this point, assume the symbols for the “n”outputs are representative of the data to be transmitted and capable ofbeing recovered by the mobile terminal 16.

For the present example, assume the base station 14 has two antennas 28(n=2) and the STC encoder logic 60 provides two output streams ofsymbols. Accordingly, each of the symbol streams output by the STCencoder logic 60 is sent to a corresponding IFFT processor 62,illustrated separately for ease of understanding. Those skilled in theart will recognize that one or more processors may be used to providesuch digital signal processing, alone or in combination with otherprocessing described herein. The IFFT processors 62 will preferablyoperate on the respective symbols to provide an inverse FourierTransform. The output of the IFFT processors 62 provides symbols in thetime domain. The time domain symbols are grouped into frames, which areassociated with a prefix by prefix insertion logic 64. Each of theresultant signals is up-converted in the digital domain to anintermediate frequency and converted to an analog signal via thecorresponding digital up-conversion (DUC) and digital-to-analog (D/A)conversion circuitry 66. The resultant (analog) signals are thensimultaneously modulated at the desired RF frequency, amplified, andtransmitted via the RF circuitry 68 and antennas 28. Notably, pilotsignals known by the intended mobile terminal 16 are scattered among thesub-carriers. The mobile terminal 16, which is discussed in detailbelow, will use the pilot signals for channel estimation.

Reference is now made to FIG. 13 to illustrate reception of thetransmitted signals by a mobile terminal 16. Upon arrival of thetransmitted signals at each of the antennas 40 of the mobile terminal16, the respective signals are demodulated and amplified bycorresponding RF circuitry 70. For the sake of conciseness and clarity,only one of the two receive paths is described and illustrated indetail. Analog-to-digital (A/D) converter and down-conversion circuitry72 digitizes and downconverts the analog signal for digital processing.The resultant digitized signal may be used by automatic gain controlcircuitry (AGC) 74 to control the gain of the amplifiers in the RFcircuitry 70 based on the received signal level.

Initially, the digitized signal is provided to synchronization logic 76,which includes coarse synchronization logic 78, which buffers severalOFDM symbols and calculates an auto-correlation between the twosuccessive OFDM symbols. A resultant time index corresponding to themaximum of the correlation result determines a fine synchronizationsearch window, which is used by fine synchronization logic 80 todetermine a precise framing starting position based on the headers. Theoutput of the fine synchronization logic 80 facilitates frameacquisition by frame alignment logic 84. Proper framing alignment isimportant so that subsequent FFT processing provides an accurateconversion from the time domain to the frequency domain. The finesynchronization algorithm is based on the correlation between thereceived pilot signals carried by the headers and a local copy of theknown pilot data. Once frame alignment acquisition occurs, the prefix ofthe OFDM symbol is removed with prefix removal logic 86 and resultantsamples are sent to frequency offset correction logic 88, whichcompensates for the system frequency offset caused by the unmatchedlocal oscillators in the transmitter and the receiver. Preferably, thesynchronization logic 76 includes frequency offset and clock estimationlogic 82, which is based on the headers to help estimate such effects onthe transmitted signal and provide those estimations to the correctionlogic 88 to properly process OFDM symbols.

At this point, the OFDM symbols in the time domain are ready forconversion to the frequency domain using FFT processing logic 90. Theresults are frequency domain symbols, which are sent to processing logic92. The processing logic 92 extracts the scattered pilot signal usingscattered pilot extraction logic 94, determines a channel estimate basedon the extracted pilot signal using channel estimation logic 96, andprovides channel responses for all sub-carriers using channelreconstruction logic 98. In order to determine a channel response foreach of the sub-carriers, the pilot signal is essentially multiple pilotsymbols that are scattered among the data symbols throughout the OFDMsub-carriers in a known pattern in both time and frequency. Examples ofscattering of pilot symbols among available sub-carriers over a giventime and frequency plot in an OFDM environment are found in PCT PatentApplication No. PCT/CA2005/000387 filed Mar. 15, 2005 assigned to thesame assignee of the present application. Continuing with FIG. 13, theprocessing logic compares the received pilot symbols with the pilotsymbols that are expected in certain sub-carriers at certain times todetermine a channel response for the sub-carriers in which pilot symbolswere transmitted. The results are interpolated to estimate a channelresponse for most, if not all, of the remaining sub-carriers for whichpilot symbols were not provided. The actual and interpolated channelresponses are used to estimate an overall channel response, whichincludes the channel responses for most, if not all, of the sub-carriersin the OFDM channel.

The frequency domain symbols and channel reconstruction information,which are derived from the channel responses for each receive path areprovided to an STC decoder 100, which provides STC decoding on bothreceived paths to recover the transmitted symbols. The channelreconstruction information provides equalization information to the SICdecoder 100 sufficient to remove the effects of the transmission channelwhen processing the respective frequency domain symbols.

The recovered symbols are placed back in order using symbolde-interleaver logic 102, which corresponds to the symbol interleaverlogic 58 of the transmitter. The de-interleaved symbols are thendemodulated or de-mapped to a corresponding bitstream using de-mappinglogic 104. The bits are then de-interleaved using bit de-interleaverlogic 106, which corresponds to the bit interleaver logic 54 of thetransmitter architecture. The de-interleaved bits are then processed byrate de-matching logic 108 and presented to channel decoder logic 110 torecover the initially scrambled data and the CRC checksum. Accordingly,CRC logic 112 removes the CRC checksum, checks the scrambled data intraditional fashion, and provides it to the de-scrambling logic 114 forde-scrambling using the known base station de-scrambling code to recoverthe originally transmitted data 116.

In parallel to recovering the data 116, a CQI, or at least informationsufficient to create a CQI at the base station 14, is determined andtransmitted to the base station 14. As noted above, the CQI may be afunction of the carrier-to-interference ratio (CR), as well as thedegree to which the channel response varies across the varioussub-carriers in the OFDM frequency band. The channel gain for eachsub-carrier in the OFDM frequency band being used to transmitinformation is compared relative to one another to determine the degreeto which the channel gain varies across the OFDM frequency band.Although numerous techniques are available to measure the degree ofvariation, one technique is to calculate the standard deviation of thechannel gain for each sub-carrier throughout the OFDM frequency bandbeing used to transmit data.

FIGS. 1 and 10 to 13 each provide a specific example of a communicationsystem or elements of a communication system that could be used toimplement embodiments of the invention. It is to be understood thatembodiments of the invention can be implemented with communicationssystems having architectures that are different than the specificexample, but that operate in a manner consistent with the implementationof the embodiments as described herein.

Numerous modifications and variations of the present invention arepossible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the inventionmay be practised otherwise than as specifically described herein.

1-19. (canceled)
 20. A method for operating a base station, the methodcomprising: for a two-dimensional time-frequency resource comprising aplurality of symbol durations in a time dimension and a plurality ofsub-carriers in a frequency dimension: allocating two or more zones inthe two-dimensional time-frequency resource, wherein a first of thezones is allocated for a fractional frequency reuse (FFR) type oftransmission, wherein a second of the zones is allocated for a singlefrequency network (SFN) type of transmission; for each of the zones,allocating groups of resource blocks within the zone, wherein eachresource block includes at least one of the sub-carriers; andtransmitting information defining the groups of resource blocks for eachof the zones.
 21. The method of claim 20, wherein at least a subset ofthe resource blocks in the second zone are allocated for unicast SFNtransmission.
 22. The method of claim 20, wherein at least a subset ofthe resource blocks in the second zone are allocated for multicast SFNtransmission and/or broadcast SFN transmission.
 23. The method of claim20, wherein the groups of resource blocks in the first zone areallocated in a distributed fashion.
 24. The method of claim 20, whereinthe groups of resource block in the first zone are allocate in alocalized fashion.
 25. The method of claim 20, wherein each of the zonesincludes a corresponding control channel that specifies how the groupsof resource blocks within that zone are allocated to user devices. 26.The method of claim 20, further comprising: transmitting a zoneconfiguration index, wherein the zone configuration index specifies avector whose components correspond to a default ordering of transmissiontypes, wherein, for each of the two or more zones, a number of resourceblocks allocated to that zone is specified by a corresponding componentof the vector.
 27. The method of claim 20, wherein the first zone isallocated for a localized FFR type of transmission.
 28. The method ofclaim 20, wherein a third of the zones is allocated for a distributedFFR type of transmission.
 29. The method of claim 20, wherein the zonesare non-overlapping rectangular regions with the two-dimensionaltime-frequency resource.
 30. The method of claim 29, wherein each of thezones spans the same window in time.
 31. The method of claim 29,wherein, in a next time-frequency resource, two or more additional zonesare allocated, wherein transmission types associated with the two ormore additional zones are cyclically shifted relative to transmissiontypes associated with said two or more zones.
 32. The method of claim29, wherein said two or more zones are allocated for uplink transmissionfrom mobile devices to the base station.
 33. The method of claim 29,wherein said two or more zones are allocated for downlink transmissionfrom the base station to mobile devices.
 34. A base station comprising:a processor, wherein, for a two-dimensional time-frequency resourcecomprising a plurality of symbol durations in a time dimension and aplurality of sub-carriers in a frequency dimension, the processor isconfigured to: allocate two or more zones in the two-dimensionaltime-frequency resource, wherein a first of the zones is allocated for afractional frequency reuse type of transmission, wherein a second of thezones is allocated for a single frequency network (SFN) type oftransmission; and for each of the zones, allocate groups of resourceblocks within the zone, wherein each resource block includes at leastone of the sub-carriers; and a transmitter configured to transmitinformation defining the groups of resource blocks for each of thezones.
 35. The base station of claim 34, wherein at least a subset ofthe resource blocks in the second zone are allocated for unicast SFNtransmission.
 36. The base station of claim 34, wherein at least asubset of the resource blocks in the second zone are allocated formulticast SFN transmission and/or broadcast SFN transmission.
 37. Anon-transitory memory medium for operating a base station, wherein thememory medium stored program instructions, wherein the programinstructions, when executed by a processor, cause the base station toimplement: for a two-dimensional time-frequency resource comprising aplurality of symbol durations in a time dimension and a plurality ofsub-carriers in a frequency dimension: allocating two or more zones inthe two-dimensional time-frequency resource, wherein a first of thezones is allocated for a fractional frequency reuse type oftransmission, wherein a second of the zones is allocated for a singlefrequency network (SFN) type of transmission; for each of the zones,allocating groups of resource blocks within the zone, wherein eachresource block includes at least one of the sub-carriers; andtransmitting information defining the groups of resource blocks for eachof the zones.
 38. The non-transitory memory medium of claim 37, whereinat least a subset of the resource blocks in the second zone areallocated for unicast SFN transmission.
 39. The non-transitory memorymedium of claim 37, wherein at least a subset of the resource blocks inthe second zone are allocated for multicast SFN transmission and/orbroadcast SFN transmission.